Wireless networks may have a need to transition from second generation (2G) systems such as GSM/GPRS/Edge to enhanced third generation (3G) systems such as UMTS (Universal Mobile Telecommunications System). UMTS uses a WCDMA air interface, instead of a TDMA air interface in GSM. 3G systems have both circuit switched (CS) and packet switched (PS) transport services. CS services implement a dedicated connection (circuit) between users. PS services, in contrast, provide more efficient utilization of the frequency spectrum by time sharing a pool of network resources. However, PS services are more prone to variable transport delay and possible data loss due to congestion at switching nodes.
Wireless networks are being upgraded to UMTS. Since UMTS deployments are not complete, in general, these wireless networks are dual mode, GSM and UMTS. As mobile users transit out of UMTS (3G) coverage cells, the wireless units will fall back to GSM/GPRS/Edge (2G) mode. Conventional handoff procedure is for the UMTS radio network controller (RNC), which controls base stations, to first commence compressed mode (CM) to enable user equipment (UE) to perform signal quality measurements and to report the best available GSM cells prior to cell change order (CCO). Compressed mode requires significant network resources and it is not necessary for packet switched (PS) services which are delay tolerant.